In terms of both chemistry and diet and nutrition, non-starch polysaccharides are a type of carbohydrate.

When to say "non-starch polysaccharides" and when to say "dietary fibre" (or equivalent):

Although these expressions refer to the same chemicals, some textbooks use them inter-changeably.

In general, 'dietary fibre' is used when describing and discussing NSPs in the diet, e.g. their functions and benefits and how they are processed by the human digestive system. 'Non-starch polysaccharides' are usually referred to when describing and explaining the chemistry, and therefore also the chemical reactions of NSPs. Obviously these areas are closely related because the digestive process includes chemical digestion e.g. due to the actions of acids, enzymes and bile.

The page about dietary fibre mentions types of dietary fibre, the functions and benefits of dietary fibre and sources of dietary fibre with examples of high fibre foods and low fibre foods.

This page about non-starch polysaccharides explains the general chemical structure of NSPs as compared with e.g. monosaccharides and disaccharides. It also lists examples of specific NSPs.

Although the general properties of polysaccharides include insolubility in cold water, no taste, and indigestible to humans, polysaccharides do play an important role in the human digestive system - as described on the page about dietary fibre.

Main types of polysaccharides:

There are many types of polysaccharides found in plant materials commonly included in human diets.

Important examples include:

1.

Starch

Chemically, consists of long chains of glucose (a monosaccharide, see above) molecules

Formed by plants during photosynthesis

Present in many plant-based food sources, such as root vegetables. e.g. potatoes, cereals e.g. and pulses.

2.

Dextrin

Formed when starchy foods (i.e. foods that contain starch, such as bread or potatoes) are baked or toasted. Dextrin is formed as part of the dry 'crust'

Dextrin is more soluble than starch

3.

Cellulose

Chemically, consists of long chains of glucose (a monosaccharide - see above) molecules

Forms the structure of some plants

Indigestible by humans but digestible by some other animals.

Valuable in human diet as source of dietary fibre - which used to be known as "roughage"

4.

Pectin

Present in the roots and/or fruits of certain plants e.g. types of plums and apples

Pectin forms a gel in water and has uses for setting jam and making various sweet foods.

Sometimes used as a vegan alternative to gelatin (also known as gelatine) in the preparation of "set" or glazed foods because the beef (cow) or pork (pig) origin of gelatin is not acceptable as an ingredient in food products to some people.

Pectin forms a complex polysaccharide

5.

Glycogen

The stored form of glucose (glucose is a monosaccharide - see above) present in animals including humans.

Energy store within the body, stored within muscles and the liver and brain

Humans store sufficient glycogen for 24 hours

In terms of their chemical composition and properties, non-starch polysaccharides are:

compounds that can be classified within the categories of the above table except for (i.e. excluding) starches.

For comparison:

Starch is the most common carbohydrate in the human diet. It is one type of polysaccharide. There are many different starches. Their sizes and shapes are characteristic of the plant that produced them, e.g. potatoes, bananas, beans (e.g. lentils, peas and chickpeas), barley, breadfruit, oats, oca, chestnuts, water chestnuts, wheat, yams, corn (maize) and rice.
In all cases pure starch is a white, tasteless and odourless powder that is insoluble in cold water or alcohol. Starch is not readily digested by humans but it is more easily digested after it has been cooked in the presence of water e.g. in bread, pancakes, noodles, pasta and porridge.

Glycogen has a similar composition to that of starch. An important difference is that it is made (from glucose) by animals rather than by plants. Although small amounts of glycogen are stored in the body as an energy reserve it is insignificant in terms of humans dietary intake because glycogen stored in animal tissue breaks back down to glucose after an animal's physical death.

Non-starch polysaccharides therefore include cellulose (which forms the bulky structure of many plants) and pectins (which come from e.g. the stones of many fruits).

Examples of non-starch polysaccharides:

This list of compounds classed as non-starch polysaccarides (NSP)s is not complete but includes examples of common NSPs.

Above: Pectins come from the stones of many fruits

alginates

arabinoxylans

beta-glucans

cellulose

chitins

gellan

guar

inulin

lignin

pectin

xanthan

and some other carbohydrates with β-glycosidic linkages.

Some sources also include certain oligosaccharides as 'types of non-starch polysaccharides'. That is understandable because oligosaccharides consist of molecules whose structure is more than two monosaccharide molecules joined together. However, oligosaccharides are increasingly classified separately from polysaccharides so their inclusion in lists of 'examples of NSPs' might cause confusion.